A state-of-the-art review of normal and extreme flow interaction with spur dikes and its failure mechanism

River protection structures, especially spur dikes, play a vital role in the hydrodynamic and morphological changes in a river system. Since the earliest days, numerous studies have been carried out to understand the flow characteristics around spur dikes by varying the spacing between them, the length, the shape, the permeability, and the submergence. Despite several studies, knowledge of flow characteristics around spur dikes is still poorly understood, resulting in damages and failures worldwide. Furthermore, such failures get aggravated under extreme conditions like floods, land-slide-induced surges and tidal bores. Therefore, this state-of-the-art review paper provides a comprehensive account of relevant studies on the flow interaction and its characteristics in the vicinity of spur dikes during normal and extreme scenarios. Possible failure mechanisms with a detailed examination of scour in the proximity of spur dikes are deliberated. Suitable design features and international standards of various types of spur dikes are appraised through this comprehensive review. Furthermore, we also identified a number of research gaps that need immediate attention. This review paper, as a whole, provides concrete knowledge of the flow interaction with spur dikes and design components of spur dikes, thereby helping researchers to understand the advancement in the research area and providing hydraulic engineers with guidance for designing the spur field at a specific site based on the requirements.